He served within the put up for six years from 1997, and had beforehand been press secretary to Conservative prime minister John Main between 1994 and 1996.
Ms Pierce wrote that he was “an important diplomat and an important character”.
“All our ideas are with Catherine and his household,” she added.
Sir Christopher launched his memoirs, DC Confidential, in 2005 recounting his time as Ambassador.
It included sharp criticism of former prime minister Tony Blair for his dealing with of the interval main as much as the Iraq Struggle.
The Day by day Mail reported Sir Christopher suffered a stroke whereas on vacation along with his spouse within the French Alps.